Smoking meat as a way of preservation and its flavor enrichment has been known for centuries.
The usual method was to place the meat to be smoked into a smoke produced by burning or smoldering coal, wood, wooden chips, or sawdust. Such process would last for several hours or even days before a sufficient amount of smoke particles were deposited on the surface of the object to be smoked. Undeposited smoke would then be freely released into the atmosphere contributing to overall air pollution. The efficiency of capturing and applying smoke using such a method was very low since most of the generated smoke would be released into the air. Better efficiency was achieved by obtaining so called liquid smoke in a process comprised of burning wood and mixing the smoke with counter streaming water or steam. Such method is disclosed in U.S. Pat. No. 3,106,473 |(Aqueous Smoke Solution For Use In Food—Hollenbeck). Other methods include burning of sawdust and condensing the products of such combustion as described in the U.S. Pat. No. 4,883,676 (Method of forming liquid smoke—Spyros Sophianopoulos et al). The yield of liquid smoke as referred in U.S. Pat. No. 3,106,473 is 100 ml from 10 g of maple sawdust (wood consumption ratio 0.1 g/ml), and can be considered as the common yield.
Compared to the older methods, less smoke is released into the atmosphere during referenced processes. Still, air pollution could be significant, while the yield of liquid smoke is lower than possible.
A similar principle to the one disclosed in this invention is described in U.S. Pat. No. 3,480,466 (Preparation and Use of a Smoke-flavored Edible Oil).